Roof Membrane R Value

Always check with your local code authority.

Roof membrane r value.

Here s a handy r value table that covers most types of roof coverings building insulation and a few other materials. The amount shown is an average amount used for roof system r value calculations. The tables show a u value r value and c value for several thicknesses of siplast roof insulation systems. For example while optimum performance using a black membrane the assembly must utilize insulation with an r value of 29.

R value is calculated by more than just the insulation. 1 000 sq ft 500 sq ft. To calculate the r value of a roof system your contractor will take into account the underlayment coverboards adhesives insulation and even the membrane. What are common r values.

Gaf analyzed membrane samples from roofs across the us and studied thickness over scrim surface cracking and the ability to repair aging tpo membranes. P roduct sizes dim ensions and w idths are nom inal values and are subject to norm al m anufacturing packaging tolerance and variation c olors f u ll r oll s ize f u ll r oll w eigh t h alf r oll s ize h alf r oll w eigh t w hite t an g ray 10 x 100 256 lbs. The u value includes the thermal resistance values for roofing and both inside and outside air films in addition to the insulation material. Both types have an r value ranging from 4 r to 6 r per 1 inch of insulation thickness.

The membrane is attached using 12 o c. Quite the contrary in colder regions ashrae zones 4 through 8. You should of course see the manufacturer provided technical data sheet for the r value of specific products. The average r value for some common roof materials include.

Please note that the r values for roof membranes shingles tiles air films and roof deck materials might or might not be permitted by your local code to be included when total roof assembly r value is being calculated for the purpose of satisfying energy code requirements. A recent study of everguard tpo roofs installed between 8 and 16 years ago found they all performed above astm standards for newly manufactured tpo. Roof membrane available in 40 50 and 60 mil thickness. For white and black membranes the table outlines the necessary adjustments in r values to maintain a roof assembly s energy performance.

Sprayed polyurethane foam spf will have an r value of 7 14 when it is newly installed. Duro last 50 mil membrane is manufactured with 28 mil of thickness on the top performance layer far exceeding industry standards as well as competitor systems with equal and even greater mil values. Pattern with perimeter sheets attached 6 o c. A u value incorporates the total system approach to insulation design.

For a very good introductory overview article on r value see r values over at the website of. 5 x 100 128 lbs. Extruded expanded polystyrene insulation is commonly used in inverted roof membrane assemblies irma. R oll s ize n ote.